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Multi-phase simulation of infected respiratory cloud transmission in air

Contribution of the Hydraulics group of the Polytechnic University of Bari to the fight against COVID-19

From the paper: Diana De Padova and Michele Mossa, Multi-phase simulation of infected respiratory cloud transmission in air, AIP Advances 11, 035035 (2021); https://doi.org/10.1063/5.0047692

In the face of the increasing death toll from the COVID-19 global pandemic, countries around the world have instituted restrictive measures to mitigate the serious effects of the pandemic. Human-to-human transmission of COVID-19 occurs primarily through large droplets that are expelled with sufficient momentum to directly contact the recipients’ mouth. Therefore, the physics of flow is central to transmission of COVID-19. Respiratory infections increase the frequency of violent expiration, including coughing and sneezing, which are particularly effective in dispersing virus-carrying droplets. Moreover, the high viral load in droplets of asymptomatic hosts that are expelled during respiratory activities, is contributing to the rapid growth of COVID-19 global pandemic. The present study uses 2D smoothed-particle-hydrodynamics multiphase simulations of the fluid dynamics of violent expiratory events in order to obtain a deeper understanding of the multi-phase nature of respiratory clouds, which can help determine separation distances from an infected person needed to minimize respiratory transmission. Our results indicate that there are three phases of jet cloud flow: the first is dominated by no-buoyancy jet-like dynamics characterized by a high speed, the second is dominated by negative buoyancy, and the third is dominated by gravity that deflects the cloud downward. Moreover, two modes of jet behavior that differ in dilution have been identified to be a function of distance from the human mouth. This work is of direct relevance to studies on the spread of COVID-19 and similar outbreaks in the future.
The movie shows the sneeze of the configuration T2 of the numerical simulations of the paper.

Diana De Padova, Michele Mossa

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This web site was launched by Prof. Michele Mossa of the Polytechnic University of Bari (Italy) with the initial support of Fondazione Caripuglia, Bari, Italy for the Research Project LIC-MON of 2003 and of the Project IMCA (Integrated Monitoring of Coastal Areas) financed by MIUR PON D.M. 593/00. Later, the initiative was supported with other Prof. Michele Mossa’s funds, most recently provided by the RITMARE Project.

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